jacked up the cab enough to get the bushing out. Have an inch of the bolt sticking out but cannot get it to break loose. Actually the "nut" is moving but not spinning. It's so frustrating.

 

Chemicals. Drown it several times a day, for a couple days, and see if it wants to break loose. If not, may have to cut the floor so your can get access from above to hold the nut in place.

 

chemicals or HEAT.
being a bolt shaft you will need to heat it up pretty good over a longer period of time so heat transfers to the nut.

what might help is once it gets hot tighten instead of loosening the bolt to get some of the dirt in the threads out of the nut. then slowly work the bolt back and forth and slowly work it out that way.
as someone else posted. removing the carpet and cutting a hole in the floor to get heat or chemicals to the nut that bolt threads into would speed up the removal process.

 

If the spot is accessible, and you have a friend with a welder, welding a small not on the end of the broken bolt is an option as well. The heat from the welder will burn off oxidation that’s bonded the two metals (the bolt and nut cert on the body. Follow up with some penetrating oil. Like the previous person had said chemicals and heat. Another option is using a simple soldering torch with map gas and penetrating oil. If there’s clearance, possibly getting a set of vice grips on there once you’ve applied heat and chemical might help.

Tap and die works too, but like it was mentioned it’s a pain in the ***. Use quality bits, use oil to reduce the heat, and go slow.

 

Success! Soaked it with PB Blaster and used a stud extractor to work it loose. Took 3-4 times worth a half hour between to finally get it moving.

 

I’ve got the identical problem going on right now. Just wondering about jacking the cab up to get clearance for the new hardware....is there enough tolerance on everything to just jack it up or are there other considerations and R&R work to do? Thanks in advance!